The conventional recording-type information recording medium (recording-type media) is designed as follows. That is, in the recording-type information recording medium, firstly, contents such as movie contents which allow free copy that does not need copyright protection, so-called copy-free contents are recorded on the basis of e.g. a DVD-Video format, and a finalize process can be performed. In addition, on the recording-type information recording medium on which the finalize process has been performed, reproduction can be performed while retaining reproduction compatibility by a conventional reproducing apparatus, such as a DVD player.
On the other hand, in the DVD-Video format, the copyright protection is realized by an encryption system, such as a CSS (Content Scramble System). Specifically, if the contents whose copyright is protected by the CSS are recorded onto the recording-type information recording medium, the reproduction of the contents is not allowed by a reproduction restriction system for protecting the copyright of the contents held by the reproducing apparatus, and the reproduction of the contents is prohibited without exception. In other words, in general, the conventional reproducing apparatus recognizes that the contents whose copyright is protected by the CSS are basically recorded in advance only on a read-only information recording medium, such as a DVD-ROM. Thus, the conventional reproducing apparatus judges that the contents are illegally copied in violation of the DVD-Video format if the contents whose copyright is protected by the CSS are recorded on the recording-type information recording medium. Then, the reproduction of the contents is not allowed by the reproduction restriction system, and the reproduction of the contents is prohibited without exception. In addition, the judgment of whether or not to be the recording-type information recording medium is based on whether or not a signal is detected from wobble (hereinafter referred to as a “wobble signal” as occasion demands) unique to the recording-type information recording medium.
More specifically, as shown in FIG. 17, under the encryption system, such as a CSS, the contents are encrypted and decrypted in the following procedure. The contents, such as video and audio, are firstly MPEG-coded by an authoring company. Then, the MPEG-coded contents are encrypted by a title key (i.e. encryption 1) by a disc manufacturer, and are recorded onto the information recording medium, such as a DVD Video disc, as encrypted contents (refer to a right-shaded portion in FIG. 17). Then, the title key is encrypted by a disc key (i.e. encryption 2) by a copyright manager (e.g. DVD CCA) and is recorded onto the information recording medium as an encryption title key. In substantially the same manner, the disc key is also encrypted by a master key set (encryption 3) by the copyright manager and is recorded onto the information recording medium as an encryption disc key set.
On the other hand, a general information recording/reproducing apparatus, such as the reproducing apparatus, generates the disc key by decrypting the encryption disc key set (i.e. decryption 1), which is recorded on the information recording medium, such as a DVD Video disc. The generated disc key allows the encryption title key to be decrypted (i.e. decryption 2) and the title key to be generated. Lastly, the generated title key allows the encrypted contents to be decrypted (i.e. decryption 3), the contents, such as video and audio, to be generated, and the contents to be reproduced.    Patent document 1: Japanese Patent Application Laid Open NO. 2004-55079    Patent document 2: Japanese Patent Application Laid Open NO. 2001-307427    Patent document 3: Japanese Patent Application Laid Open NO. 2001-357001    Patent document 4: Japanese Patent Application Laid Open NO. 2000-311346    Non-patent document 1: “Protection of Contents on DVD”, Toshiba Review, Vol. 58, No 6 (2003).